FARNBOROUGH, England — As a top Delta executive confirmed an expected order at the Farnborough Air Show for 100 Boeing 737 Max 10s — with options to purchase another 30 on similar terms — he said it was a “delicate moment” that marked a positive turn in a relationship that had gone awry. Mahendra Nair, senior vice president at Delta responsible for its aircraft fleet, also declared the commonality of the Max 10 cockpit systems with other 737s “the biggest factor that drove the decision” to buy. With that, Nair offered full support for Boeing’s position that Congress should act to ensure that t…